Hollow glass articles, such as bottles and jars, when molded by a forming machine of the I.S. type, are molded in two steps. In the first step, a preform of the finished container, which is usually called a blank or a parison, is molded by an annular mold made up of a pair of mating blank mold sections. Upon the completion of the blank molding step, the blank mold sections separate and the blank or parison is transferred to another mold station, often called the blow mold station, where it is blown into its final shape by another annular mold that is made up of another mating pair of mold sections. At the conclusion of the blow mold process, the mating sections of the blow mold are separated, and the container is removed from the forming machine for further processing.
The glass gob that is formed into a parison in the blank mold of an I.S. machine is sufficiently hot to be capable of being shaped into a blank and, thus, possesses a high level of latent heat. Much of this heat must be removed before the container is removed from the blow mold of the forming machine, however, so that the finished container will be sufficiently rigid to undergo further processing without any further change in its shape. Thus, much heat must be removed from the container being formed, both during the blank molding step and the blow molding step, and unless the heat is removed at a rapid rate, the productivity of the forming machine is unduly limited. The problem of heat removal from the molds of an I.S. forming machine at a suitable rate is especially important at the blank mold station because the surface area of the parison is quite small due to the small diameter of the parison, which limits the rate at which heat can be removed, and the amount of heat to be removed is quite high due to the larger wall thicknesses of the parison in comparison to the wall thicknesses of a finished container.
Various prior artisans have addressed problems encountered in cooling glass articles being formed by an I.S. machine, as disclosed by U.S. Pat. Nos. 3,887,350 (Jenkins), 4,657,573 (Jones), 4,668,269 (Cantu-Garcia et al.), 4,690,703 (Kulig), 4,783,212 (Loffler) and 5,364,437 (Bolin), the disclosure of each of which is incorporated by reference herein. The problems with the aforesaid and other prior art approaches to mold cooling of I.S. machine molds is that they add considerably to the complexity, and thus the cost, of the forming machine molds, each set of which is especially designed for only a single type of product. Thus, it is advantageous to incorporate as much of the required mold cooling structure in other structure of an I.S. molding machine that does not need to be changed every time a set of molds is replaced to permit the machine to manufacture containers of a different type, size or design.